The record-setting March warmth doesn't mean the trend will continue. However, Dev Nyogi, state climatologist for Indiana, issued a statement saying that overall, the warmer than normal trend should continue through June. He also sees drier than normal conditions until May and June, when it returns to normal. However, precipitation totals have been fickle, with some parts of central and southern Indiana already receiving heavy rains at the end of March and first of April.
Despite the trend, Nyogi is quick to point out that there still could be frost at any time. He also said that the risk of severe weather, including tornadoes, which broke out with one of the deadliest ever in Indiana on March 2, remains above normal for the spring.
Short –term returns to something other than the overall trend is always possible. That's why it's too early to rule out frost. However, averages begin to play on your side if you're wanting to plant early, especially in light of the forecast. For example, the average date of the last 32 degree F temperature is fairly low in the southern half of the state from this date forward. It still remains relatively high in parts of northern Indiana, except along the edge of Lake Michigan where Lake effect weather overrides other conditions.
What caused the unusual March and will likely to continue to influence weather is a factor called the Artic Oscillation, notes Ken Scheeringa, assistant weather ag climatologist. It snuck up on weather forecasters who were only looking at the LaNina and El Nino cycle. That one relates to Pacific Ocean temperatures near the equator that create atmospheric pressure differences and affects air circulation patterns aloft. It is typically a dominating factor, but not always. So far this year, it is being offset and overridden by the Arctic Oscillation factor, which turned out to be 180 degrees different than a year ago.